Hi Guys
Has anyone tried the silver conductive pens about?
My first experience to test one didn’t go well.
All I can say is I want my money back!

I can’t say how long this was sitting on the shelf at the store,
but I did use it the same night I purchased it.

 

Wouldn't it be nice to just draw out your circuit and have at it? Sorry to say I have never seen such a thing actually work in practice.

I tried such a pen years and year back to just fix a trace, to fill in a small break. Eventually I scraped off that muck and used some solder and a small piece of wire to jump the gap.

 

Don't you have to let it dry?

There is a newer silver "ink" that deposits elemental silver nanoparticles. It reportedly has almost the conductivity of pure silver: http://pubs.acs.org/doi/abs/10.1021/ja209267c

That ink uses a modification of the well-known Tollens' reagent and is now used commercially to "print" some circuits.

John

 

It’s still set up and the first trace looks dry, but we’ll see.
There is also a new second trace as well.
You’re supposed to be able to solder to it once cured, so I’ll still have a go at that,
but it claims to be 0.02 Ohm resistance per square mm, and for this test I slopped it on thick.

I’d still have a lot more faith in something from MG Chemical or some company like that.

 

Ohms per square mm??? Resitvivity is measured in ohms per square period, no units.

Reason being a square one mm per side and a square one mile per side have the same exact resistance. The units drop out.

I used to make resistors and the compounds came rated that way. You varied the size for reasons of power dissipation, higher power needs a larger footprint.

 

Can you provide a link to the stuff you used?

The newer material definitely needs mild heating to complete the chemical reaction and drive off the volatile products. The solution as applied is actually silver ion in solution. The older material was just a suspension of metallic silver and also needs to have the carrier solvents dried. From the appearance of your ink, I suspect it is the older type of material.

John

 

Here is the link:
http://www.jaycar.com.au/silver-conductive-pen/p/NS3033

The exact quote from the rear of the pack goes like this:
<0.020ohm/sq/mil.

It says 24 hour curing OR 4 hour curing if certain heat is used to cure.

 

That MSDS indicates the ink you have is the older formulation that does not deposit metallic silver from its oxidized form. That is, the silver in the ink is in its metallic form.

John

 

What does that mean with regard to repairing PCBs?
If you tell me how to use it if anything more than curing under an incandescent lamp which I’ll try, I’ll give it every chance.
If you can solder to it (it says less than 350C, which can be done with lead solder), then that’s still useful.
If it can never conduct or take solder, that’s quite unfortunate that toxic chemicals are serving no purpose

 

I have no idea about soldering to the ink you have, as I haven ever used it. If the directions say it will work, then I would try it on some plain FR4 or other backing that will take the heat. If temperature is a problem, you might try one of the low-temp solders -- many contain bismuth in the alloy to reduce the melting point. The main problem, if there is one, will be the proprietary resins that hold the silver particles together. Burnishing the cured/dried deposit and use of flux may help.

The newer material, which was openly published in JACS with complete details in the abstract, is definitely solderable. There are no resins or other matrix left after mild heating. Unfortunately (for us), once the commercial applications were recognized, the freely available materials were removed from easy access.

Here are a couple of links that involve the nanoparticle ink (aka Tollens reaction ink) you may find interesting:
1) https://www.kickstarter.com/projects/1597902824/agic-print-printing-circuit-boards-with-home-print
2) http://diamond-jet.com/silvernanoparticleink-2.aspx (It is simple to make and very expensive to buy!)
3) http://www.instructables.com/id/Print-Conductive-Circuits-With-An-Inkjet-Printer/

I suspect you are not into doing that chemistry. Wikipedia will tell you all about the Tollens' reaction. One use was silvering telescope mirrors. The modern adaptation simply uses reagents that give volatile end products. For example, ammonium carbonate has been used for many years as a buffer in biochemistry because it is easily removed under vacuum.

I have attached my version of the recipe that appeared in JACS. I have no commercial interest in the process, but it may be covered by patents in the USA and elsewhere.

John

 

Thanks, I can see that similar substance has a shelf life which could be the cause,
but I will try to cure what I have under heat to try something different.